1. Field of the Invention
The present invention relates generally to photorefractive crystals which are used in optical computing and optical memory systems. More particularly, the present invention relates to the growth of potassium lithium tantalate niobate crystals which are suitable for use in optical computing and optical memory systems.
2. Description of Related Art
Photorefractive materials and their use in memory systems and computer networks is an area of technology which is undergoing continuing research and development. The special nature of holographic memories makes them especially well-suited for implementing unconventional computing algorithms, such as associative memories and neural networks. The value of photorefractive materials in volume holography is appreciated when it is considered that the data storage density of such holographic media is expected to be on the order of 10.sup.12 bit cm.sup.-3. In addition, the data retrieval rate from such photoreactive materials is expected to be on the order of up to 10 Gbit/sec.
It has long been recognized that potassium tantalate niobate (KTN) is a promising photorefractive material. However, the phase transition of KTN becomes first order at 220.degree. K. The first order nature of the phase transition causes substantial deterioration of the optical quality of KTN.
Potassium lithium tantalate (KLT) is a crystal which has been suggested for use in studies of solid state physics. However, the use of KLT has not been extended to optical systems.
In view of the above problems, there is a continuing need to provide new photorefractive materials which are suitable for use in a wide variety of optical systems including optical computing, optical memories, optical sensing devices and optical neural networks. Preferably, photorefractive materials should be amenable to use in such systems at room temperature in order to make them useful as a practical matter.